ABSTRACT Perinatal hypoxic-ischemic encephalopathy (HIE) affects 1 to 3 infants per every 1000 born. Mortality from HIE can be up to 20%, and approximately 25% of survivors suffer significant long -term disability including cerebral palsy, epilepsy, and developmental disorders. Damage during the acute phase of HIE is caused by a deficit in oxygen and glucose in the brain. However, increasing evidence indicates that secondary and tertiary phases are responsible for significant ongoing damage. After an initial insult, oxidative stress increases and signaling cascades lead to cell death. Elevated inflammation and epigenetic changes may be present months to years after initial injury as evidenced by myelin deficits, reduced plasticity, and altered cell number. Recently, hypothermia has been used to significantly reduce mortality and developmental complications in term infants with HIE. However, there are several limitations to this approach. Treatment must be initiated within 6 hours of injury to reduce metabolic damage and oxidative stress, and 40-50% of infants still die or suffer severe disability. The National Institute of Child Health and Human Development recently reported an urgent need to develop neuroprotective combination therapies to be used hours to days after the insult in combination with hypothermia. Several known neuroprotective compounds (erythropoietin, stem cells, xenon, etc.) are being investigated alone or in combination with hypothermia, but, to date, none have emerged as a more effective treatment for HIE. Overall, there is need for new adjuvant therapies in HIE. This project will test the efficacy of moderate hypothermia plus an immunomodulatory compound, synthetic PreImplantation Factor (sPIF), in a rat model of HIE that is equivalent in development to a term human infant brain. sPIF regulates both the innate and adaptive immune response and reverses chronic neuroinflammation. sPIF co-localizes with neuronal and macrophage cells and crosses the blood-brain-barrier during inflammation. In HIE model of prematurity sPIF reversed neuro-axonal injury, activating neuronal stems cells proliferation and differentiation to myelin coated cells. In this project, we will first perform a short-term, dose-ranging study with sPIF plus hypothermia to determine what dose is most effective. Then, we will perform a longer-term comparison of the selected sPIF dose plus hypothermia combination and compare the results to hypothermia alone. We will use histology, neurofunctional tests to compare the different treatments.Overall, we anticipate sPIF plus hypothermia will affect all injury phases and will create an additive neuroprotective effect since these treatments target different pathways. Clinical translation of sPIF as a first-line HIE treatment is promising if these preclinical evaluations are successful. BioIncept received Fast-Track FDA designation for sPIF and a safety trial in patients with autoimmune hepatitis was completed successfully.